Semiconductor package

ABSTRACT

A semiconductor package includes a die pad, a semiconductor die mounted on the die pad, a plurality of leads including a power lead disposed along a peripheral edge of the die pad, at least one connecting bar connecting the die pad, a power bar disposed on one side of the connecting bar, and a surface mount device (SMD) having a first terminal and a second terminal. The first terminal is electrically connected to the ground level through a first bond wire. The second terminal is electrically connected a power level through a second bond wire.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. application Ser. No. 14/566,689 filed Dec. 10, 2014, which itself is a continuation of U.S. application Ser. No. 13/626,899 filed Sep. 26, 2012, now U.S. Pat. No. 8,941,221B2, which claims the benefit of U.S. provisional application No. 61/541,235, filed Sep. 30, 2011. All of the above-mentioned applications are included herein in their entirety by reference.

BACKGROUND

The present invention relates generally to integrated circuit (IC) package technology. More particularly, the present invention relates to a semiconductor package including a leadframe with power bars or power ring, which is capable of improving power supply variations and suppressing power noise.

Semiconductor dies are conventionally enclosed in plastic packages that provide protection from harsh environments and enable electrical interconnection between the semiconductor die and a substrate or circuit board. Such an integrated circuit (IC) package typically includes a metal substrate or a leadframe, a semiconductor die mounted on a die pad of the leadframe, and bond wires electrically connecting bond pads on the semiconductor die to inner leads of the leadframe. The leadframe, the bond wires, and the semiconductor die are typically encapsulated in a molding compound.

The technology trends in the back-end packaging industry can be summarized as “more functionality in a smaller space”. The integrated circuit chip is becoming more and more complicated, leading to increased number of external connection pins of the leadframe package. As the pin count is increased, the cost of packaging is increased accordingly.

Further, as the integration and performance of semiconductor dies increase, the impact of power noise on I/O signaling is significant. It is desirable to provide of stable supply voltage during chip operation. Furthermore, in some circumstances, a number of bond wires extending from bond pads on a chip are bonded onto one single inner lead of a leadframe in the package. The crowded wires bonded to one single lead result in reliability and yield issues.

In light of the above, there is a strong need in this industry to provide an improved semiconductor package structure and leadframe package, which are cost-effective, particularly suited for high-speed semiconductor dies, and are capable of improving power supply variations and suppressing power noise.

SUMMARY

In one aspect, this disclosure provides a semiconductor package including a die pad, a semiconductor die mounted on the die pad, a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad, at least one connecting bar connecting with the die pad, a power bar disposed on one side of the connecting bar, and a capacitor mounted between the power bar and the connecting bar. The power bar is integrally connected to the power lead.

In another aspect, this disclosure provides a semiconductor package including a die pad, a semiconductor die mounted on the die pad, a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad, at least one connecting bar connecting the die pad, a power bar disposed on one side of the connecting bar, and a capacitor mounted between the power bar and the die pad. The power bar is integrally connected to the power lead.

In still another aspect, this disclosure provides a semiconductor package including a die pad, a semiconductor die mounted on the die pad, a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad, at least one connecting bar connecting the die pad, a ground bar disposed on one side of the connecting bar, a power bar disposed on one side of the connecting bar, wherein the power bar is integrally connected to the power lead, and a capacitor mounted between the power bar and the ground bar. The ground bar is integrally connected to the connecting bar.

In still another aspect, this disclosure provides a semiconductor package including a die pad, a semiconductor die mounted on the die pad, a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad, at least one connecting bar connecting the die pad, a power bar disposed on one side of the connecting bar, and a surface mount device (SMD) comprising a first terminal and a second terminal, wherein the first terminal is electrically connected to the ground level through a first bond wire, and wherein the second terminal is electrically connected a power level through a second bond wire. The power bar is integrally connected to the power lead.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

FIG. 1 illustrates a schematic top view of an exemplary leadframe package according to one embodiment of the invention;

FIG. 2 is an enlarged top view showing a germane portion of the leadframe package of FIG. 1;

FIG. 3 is a schematic, cross-sectional view taken along line I-I′ of FIG. 1;

FIG. 4 is enlarged top view showing a germane portion of a leadframe package in accordance with another embodiment of the invention;

FIG. 5 is a schematic, cross-sectional diagram showing a leadframe package in accordance with another embodiment of the invention;

FIG. 6 is an enlarged top view showing a portion of a leadframe package including SMD according to another embodiment of the invention;

FIG. 7 is a schematic, cross-sectional diagram showing the SMD in the leadframe package; and

FIG. 8 is a schematic, cross-sectional view showing an exemplary leadframe package including SMD according to still another embodiment of the invention.

It should be noted that all the figures are diagrammatic. Relative dimensions and proportions of parts of the drawings have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar features in modified and different embodiments.

DETAILED DESCRIPTION

The present invention pertains to an improved semiconductor package, as described below, which is suited for the applications including, but not limited to, LQFP (Low-Profile Quad Flat Pack) packaging, TQFP (Thin Quad Flat Pack) packaging, QFN (Quad Flat Non-leaded) packaging, DFN (Dual Flat No-lead) packaging, multi-zone QFN, multi-die flip-chip packaging, and other applicable packaging technology.

Please refer to FIGS. 1-3. FIG. 1 illustrates a schematic top view of an exemplary leadframe package 10 according to one embodiment of the invention. FIG. 2 is an enlarged top view showing a germane portion of the leadframe package 10. FIG. 3 is a schematic, cross-sectional view taken along line I-I′ of FIG. 1. As shown in FIGS. 1-3, in general, the leadframe package 10 includes at least one semiconductor die 12 a that is mounted on a die pad 14 and is adhered to a top surface 14 a of the die pad 14 by using an adhesive 24 such as silver paste or epoxy. According to one embodiment, the bottom surface 14 b of the die pad 14 may be exposed within the package body. The exposed bottom surface 14 b of the die pad 14 helps dissipate heat generated by the semiconductor die 12 a, which is also known as an exposed die pad or E-pad configuration. Typically, the exposed bottom surface 14 b of the die pad 14 may be used for electrically connecting to a ground layer of a printed circuit board (PCB). According to one embodiment, four slender connecting bars 142 a-142 d extend inward from respective four corners of the leadframe package 10 to support the die pad 14. Leads 16 including inner leads 116 and outer leads 126 are arranged along the peripheral edges of the die pad 14, which provide electrical connection between the semiconductor die 12 a and other devices such as a circuit board. The semiconductor die 12 a and the leadframe including the die pad 14 and the inner leads 116 are encapsulated in a molding compound 30.

According to one embodiment, the semiconductor die 12 a may be a TV chip or a system-on-a-chip (SoC) chip for digital TV applications, but should not be limited thereto. According to one embodiment, the leadframe package 10 may further include a semiconductor chip 12 b. The semiconductor die 12 a and the semiconductor chip 12 b are disposed side-by-side and are arranged on the same plane (top surface 14 a) of the die pad 14. For example, the semiconductor chip 12 b may be a DDR2 or DDR3 DRAM chip, but should not be limited thereto. According to one embodiment, the semiconductor chip 12 b may be situated farther from a V_(CCK) core power supply rail of a two-layer printed circuit board (not shown) than the semiconductor die 12 a. According to one embodiment, several rows of bond pads 123 may be provided on an active top surface 121 of the semiconductor die 12 a along four side edges thereof.

According to one embodiment, the inner leads 116 are arranged in a first horizontal plane along the peripheral edges of the die pad 14. The leadframe package 10 may further comprise a ground bar 130 downset from the first horizontal plane to a lower second horizontal plane between the inner leads 116 and the die pad 14, and a plurality of downset tie bars 144 connecting the ground bar 130 with the die pad 14. According to one embodiment, the ground bar 130 extends along at least one peripheral edge of the die pad 14 and is integrally connected to one of the connecting bars 142. Therefore, the ground bar 130, the connecting bars 142, and the die pad 14 have the same voltage potential, i.e., ground level.

In FIG. 1, for example, the leadframe package 10 comprises a first ground bar 130 a extending along at one peripheral edge segment of the die pad 14, a second ground bar 130 b extending along at two peripheral edge segments of the die pad 14, and a third ground bar 130 c extending along at two peripheral edge segments of the die pad 14, such that the first, second and third ground bars partially circumvent the die pad 14. The first ground bar 130 a with its one distal end connecting to the first connecting bar 142 a is integrally connected to the die pad 14 with a downset tie bar 144 a. A discontinuity or gap 132 is formed between the first ground bar 130 a and the second ground bar 130 b. The second ground bar 130 b is integrally connected to the die pad 14 with downset tie bars 144 b and is integrally connected to the second connecting bar 142 b. Likewise, a discontinuity or gap 132 is provided between the second ground bar 130 b and the third ground bar 130 c. The third ground bar 130 c is integrally connected to the die pad 14 with downset tie bars 144 c and is integrally connected to the third connecting bar 142 c. In this case, no ground bar is provided around the semiconductor chip 12 b.

According to one embodiment, the leadframe package 10 further comprises a power bar 160 disposed on either side of one connecting bar 142 and does not contact the connecting bar 142. That is, the power bar 160 is electrically isolated from the connecting bar 142 and provides power signal having different voltage level from ground level of the connecting bar 142. According to one embodiment, for example, the power bars 160 are flush with the inner leads 116 in the first horizontal plane and extend along the peripheral edges of the die pad 14. Each of the power bars 160 is respectively integrally connected to at least one power leads 16 a that are designated to supply power voltage such as core power.

In FIG. 1, for example, a first power bar 160 a extends substantially in parallel with the first ground bar 130 a and between the first connecting bar 142 a and the second connecting bar 142 b. The first power bar 160 a is integrally connected to one power lead 16 a. A second power bar 160 b extends substantially in parallel with the second ground bar 130 b and between the second connecting bar 142 b and the third connecting bar 142 c. The second power bar 160 b is integrally connected to two power leads 16 a. The first power bar 160 a is electrically connected to the second power bar 160 b by using connection member 28 traversing the second connecting bar 142 b. For example, the connection member 28 may comprise bond wires, conductive straps, jumpers or resistors with zero resistance (0Ω resistors), or the like. The connection member 28 does not contact the second connecting bar 142 b. A third power bar 160 c extends substantially in parallel with the third ground bar 130 c and between the third connecting bar 142 c and the fourth connecting bar 142 d. The third power bar 160 c is integrally connected to one single power lead 16 a. Likewise, the second power bar 160 b is electrically connected to the third power bar 160 c by using connection member 28 traversing the third connecting bar 142 c.

A fourth power bar 160 d extends along three peripheral edges segments of the die pad 14 between the first connecting bar 142 a and the fourth connecting bar 142 d. The fourth power bar 160 d partially circumvents the die pad 14 and is disposed adjacent to the semiconductor chip 12 b. As shown in FIG. 1, the fourth power bar 160 d is integrally connected to three power lead 16 a. The fourth power bar 160 d is electrically connected to the third power bar 160 c by using connection member 28 traversing the fourth connecting bar 142 d. Optionally, a decoupling capacitor 50 a may be mounted between the fourth power bar 160 d and the fourth connecting bar 142 d for suppressing power noise. Likewise, the fourth power bar 160 d is electrically connected to the first power bar 160 a by using connection member 28 traversing the first connecting bar 142 a. Optionally, a decoupling capacitor 50 b may be mounted between the fourth power bar 160 d and the first connecting bar 142 a and a decoupling capacitor 50 c may be mounted between the fourth power bar 160 d and the die pad 14 for suppressing power noise. According to the embodiment, the first, second, third and fourth power bars are electrically connected together so as to form a continuous power ring that completely circumvents the die pad 14, which reduces the power impedance and the power noise. However, it is to be understood that in some cases the first, second, third and fourth power bars may not be electrically connected together.

According to one embodiment, the bond pads 123 on the semiconductor die 12 a, which are also known as input/output pads or I/O pads, may generally comprise ground pads 123 a, power pads 123 b, and signal pads 123 c, etc. The bond pads 123 are electrically coupled to corresponding ground bar 130, the inner leads 116, or the power bar 160 through bond wires 18. For example, the ground pads 123 a are electrically coupled to the ground bar 130 through the bond wires 18 a, the power pads 123 b are electrically coupled to the power bar 160 through the bond wires 18 b, and the signal pads 123 c are electrically coupled to the inner leads 116 through the bond wires 18 c. More bond wires can be bonded due to the larger area of the power bar that will improve the crowded wires bonded to one single lead resulting in reliability and yield issues.

FIG. 4 is enlarged top view showing a germane portion of a leadframe package in accordance with another embodiment of the invention. FIG. 5 is a schematic, cross-sectional diagram showing a leadframe package in accordance with another embodiment of the invention, wherein like regions, layers or elements are designated by like numeral numbers. As shown in FIG. 4 and FIG. 5, the connecting bar 142 has a downset structure 242. A downset structure 260 is provided between the power lead 16 a and the power bar 160, such that the power bar 160 can be coplanar with the ground bar 130. A decoupling capacitor 50 d is mounted between the power bar 160 and the downset connecting bar 142 and a decoupling capacitor 50e is mounted between the power bar 160 and the ground bar 130.

To sum up, this disclosure at least contains the following benefits and advantages. 1). Lower power impedance can be achieved because more power wires can be bonded on a large area of the power bars. 2). Shorter decoupling path due to the incorporation of the in-package decoupling capacitors. 3). Higher assembly yield can be achieved due to relief of the power wires density on the power bar. 4) Less power lead is possible because additional power ring is added to reduce power impedance.

According to the embodiments of the invention, a wire-bondable surface mount device (SMD) may be mounted basically anywhere in the leadframe package. For example, the SMD may be mounted on the semiconductor die surface, on the die pad, on the ground bar, power bar, on the inner leads, or on the lead lock tape. The non-conductive lead lock tape is used to maintain lead coplanarity. The SMD may be mounted in the semiconductor package by using a non-conductive paste.

Please refer to FIG. 6 and FIG. 7. FIG. 6 is an enlarged top view showing a portion of a leadframe package 10 a including SMD according to another embodiment of the invention, wherein like regions, layers or elements are designated by like numeral numbers. FIG. 7 is a schematic, cross-sectional diagram showing the SMD in the leadframe package. As shown in FIG. 6 and FIG. 7, a SMD 300 may be mounted on the inner leads 116 and the connecting bar 142 through a non-conductive paste (an adhesive layer, a film, a polymer, or a lead lock tape) 320, but is not limited thereto. According to the embodiments of the invention, the SMD 300 may comprise a passive discrete device such as a resistor, an inductor, a capacitor, an RLC (resistor-inductor-capacitor) device, an ESD (electrostatic discharge) device, an IPD (integrated passive device), a crystal oscillator device, or the like.

According to the embodiments of the invention, the SMD 300 has two terminals: the first terminal 302 and the second terminal 304. The first terminal 302 may be electrically connected to the ground level such as ground pads 123 a on the semiconductor die 12 a, the ground bar 130 c, the die pad 14, the connecting bar 142 c, or ground leads of the leads 16 through the bond wires 402. The second terminal 304 may be electrically connected to the power level such as the power pads 123 b on the semiconductor die 12 a, the power bar 160 b, or power leads 16 a through the bond wires 404. The more wires and shorter wires are bonded or connected, the less power and ground impedance can be achieved. Preferably, at least three bond wires are bonded to each terminal of SMD 300. Preferably, each bond wire has a wire length less 6mm. The first terminal 302 and the second terminal 304 may include external electrodes plated with noble metal, such as gold (Au), silver (Ag), platinum (Pt), or palladium (Pd),but is not limited thereto. In order to reduce the material cost and improve the wire bondability or solderability and adhesion with non-conductive paste in the package, the thickness of the noble metal covered on the terminals 302 and 304 is preferably less than 6 pm.

FIG. 8 is a schematic, cross-sectional view showing an exemplary leadframe package 10 b including SMD according to still another embodiment of the invention, wherein like regions, layers or elements are designated by like numeral numbers. As shown in FIG. 8, the SMD 300 may be mounted on the active top surface 121 of the semiconductor die 12 a. Optionally, the SMD 300 may be coupled to a substrate (or a circuit board) 500. The substrate 500 may comprise single-layer or multi-layer traces, via-plug, solder resistance layer, wiring or circuit patterns, but is not limited thereto. Bond wires 402 and 404 maybe bonded to the circuit patterns (e.g. bonding pads) on the substrate 500 or the terminals of the SMD 300.

The semiconductor die 12 a further comprises a plurality of I/O or power pads 133 on the other side of the SMD 300, which provide the power supply or signal input/output to the central part of the semiconductor die 12 a and are opposite to the peripheral (I/O) bond pads 123. According to the embodiments of the invention, likewise, the SMD 300 may have at least two terminals: the first terminal 302 and the second terminal 304. The first terminal 302 maybe electrically connected to the ground level such as ground pads 123 a on the semiconductor die 12 a, the ground bar 130, the die pad 14, the connecting bar, or ground leads of the leads 16 through the bond wires 402. The second terminal 304 may be electrically connected to the power level such as the power pads 133 on the semiconductor die 12 a, the power bar 160, or power leads 16 a through the bond wires 404. The first terminal 302 and the second terminal 304 may include external electrodes plated with noble metal, such as gold (Au), silver (Ag), platinum (Pt), or palladium (Pd), but is not limited thereto. A continuous wire bonding configuration consisting of the bond wires 404 a and 404 b is provided between the power leads 16 a and the power pads 133, which utilizes the second terminal 304 as a jump or relay pad such that the path resistance or channel impedance can be reduced and better power integrity can be achieved. In some embodiments of the present disclosure, the SMD 300 may be an integrated passive device (IPD) with at least four terminals including the power, the ground and the radio frequency (RF) input/output signals, which are electrically connected to the power pad 123 b, the ground pad 123 a, the I/O pads 123 on the active top surface 121 of the semiconductor die 12 a or circuit patterns of the substrate 500.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

What is claimed is:
 1. A semiconductor package, comprising: a die pad; a semiconductor die mounted on the die pad; a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad; at least one connecting bar connecting with the die pad; a power bar disposed on one side of the connecting bar, wherein the power bar is integrally connected to the power lead; and a capacitor mounted between the power bar and the connecting bar.
 2. A semiconductor package, comprising: a die pad; a semiconductor die mounted on the die pad; a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad; at least one connecting bar connecting the die pad; a power bar disposed on one side of the connecting bar, wherein the power bar is integrally connected to the power lead; and a capacitor mounted between the power bar and the die pad.
 3. The semiconductor package according to claim 2, wherein the power bar is flush with the die pad.
 4. A semiconductor package, comprising: a die pad; a semiconductor die mounted on the die pad; a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad; at least one connecting bar connecting the die pad; a ground bar disposed on one side of the connecting bar, wherein the ground bar is integrally connected to the die pad; a power bar disposed on one side of the connecting bar, wherein the power bar is integrally connected to the power lead; and a capacitor mounted between the power bar and the ground bar.
 5. The semiconductor package according to claim 4, wherein the power bar is flush with the ground bar.
 6. A semiconductor package, comprising: a die pad; a semiconductor die mounted on the die pad; a plurality of leads comprising a power lead disposed along a peripheral edge of the die pad; at least one connecting bar connecting the die pad; and a surface mount device (SMD) comprising a first terminal and a second terminal, wherein the first terminal is electrically connected to the ground level through a first bond wire, and wherein the second terminal is electrically connected a power level through a second bond wire.
 7. The semiconductor package according to claim 6, wherein a bottom surface of the die pad is exposed outside the semiconductor package.
 8. The semiconductor package according to claim 6 further comprising a molding compound at least partially encapsulating the die pad, and the leads.
 9. The semiconductor package according to claim 6, wherein the SMD is mounted in the semiconductor package by using a non-conductive paste.
 10. The semiconductor package according to claim 6, wherein the SMD overlaps with and electrically isolated from the leads.
 11. The semiconductor package according to claim 6, wherein the first terminal is electrically connected to a ground pad on the semiconductor die, a ground bar, the die pad, the connecting bar, or a ground lead of the leads.
 12. The semiconductor package according to claim 6, wherein the second terminal is electrically connected to power pads on the semiconductor die, a power bar, or the power lead of the leads.
 13. The semiconductor package according to claim 6, wherein the SMD is mounted on an active top surface of the semiconductor die.
 14. The semiconductor package according to claim 6, wherein the SMD is mounted on the die pad.
 15. The semiconductor package according to claim 6, wherein the SMD is mounted on a substrate.
 16. The semiconductor package according to claim 15, wherein the substrate comprises single-layer or multi-layer traces, wiring, via-plug or circuit patterns.
 17. The semiconductor package according to claim 6, wherein the SMD comprises a passive discrete device.
 18. The semiconductor package according to claim 17, wherein the passive discrete device comprises a resistor, an inductor, a capacitor, an RLC (resistor-inductor-capacitor) device, an ESD (electrostatic discharge) device, an IPD (integrated passive device), or a crystal oscillator device.
 19. The semiconductor package according to claim 6, wherein the first terminal and the second terminal of the SMD are plated with noble metal comprising gold (Au), silver (Ag), platinum (Pt), or palladium (Pd). 